Rowan v. United States Post Office Department
Rowan v. Post Office Dept., 397 U.S. 728 (1970), is a case in which the United States Supreme Court ruled that an addressee of postal mail has sole, complete, unfettered and unreviewable discretion to decide whether he or she wishes to receive further material from a particular sender, and that the sender does not have a constitutional right to send unwanted material into someone's home.
Source: Wikipedia — Rowan v. United States Post Office Department (CC BY-SA 4.0)